diff --git a/socorro/siglists/prefix_signature_re.txt b/socorro/siglists/prefix_signature_re.txt
index 73c78f6be9..34b71e3fda 100644
--- a/socorro/siglists/prefix_signature_re.txt
+++ b/socorro/siglists/prefix_signature_re.txt
@@ -87,6 +87,7 @@ mozilla::detail::ConditionVariableImpl::.*
 SleepConditionVariableSRW
 mozilla::TimeStamp::Now
 GetTickCount64
+mozilla::detail::MutexImpl::.*
 mozilla::detail::nsStringRepr::First
 mozilla::detail::nsStringRepr::Last
 mozilla::ipc::LogicError